Finishing tool

ABSTRACT

A tool according to the invention is to be used for finishing internal surfaces of revolution in blanks by the method of plastic deformation. The tool body is provided, at its peripheral surface with a groove for accommodation of deforming members which are caused to move under the action of fluid under pressure. For supplying fluid under pressure, passages are made in the body of the tool communicating the groove with a source of fluid under pressure. Thus, each deforming member performs a compound movement during the machining, whereby the force required for finishing of the surface by the method of plastic deformation is reduced.

United States Patent Minakov et a1.

[4 1 Oct. 14, 1975 [54] FINISHING TOOL Filed: Dec. 12, 1974 Appl. No.:532,002

[52] US. Cl 72/76; 72/120 [51] Int. Cl. B21D 41/02 [58] Field of Search72/75, 76, 112, 120, 53;

Primary Examiner-Lowell A. Larson Attorney, Agent, or FirmHolman & SternABSTRACT A tool according to the invention is to be used for finishinginternal surfaces of revolution in blanks by the method of plasticdeformation. The tool body is provided, at its peripheral surface with agroove for accommodation of deforming members which are caused to moveunder the action of fluid under pressure. For supplying fluid underpressure, passages are made in the body of the tool communicating thegroove with a source of fluid under pressure. Thus, each deformingmember performs a compound movement during the machining, whereby theforce required for finishing of the surface by the method of plasticdeformation is reduced.

3 Claims, 13 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of43,911,707

FIE. 2

FIE]

US. Patent Oct. 14, 1975 Sheet 2 of4 3,911,707

' FIG. 7

US. Patent Oct. 14, 1975 Sheet 3 of4 3,911,707

U.S. Patent Oct. 14, 1975 Sheet 4 of4 3,911,707

FINISHING TOOL The present invention relates to tools to be used formachining by the method of plastic deformation of metallic blanks, andin particular to tools for finishing internal surfaces of revolution inblanks.

The present invention may be widely used in the mechanical engineeringfor machining internal surfaces of actuating cylinders, cylinder linersfor engines, precision cylinders for measuring equipment, internalsurfaces of bearing races.

The invention may be the most advantageously used in machining internalsurfaces of thin-walled blankshaving cylindrical, elliptical, sphericaland conical surface with a curvilinear or undulated generatrix, as wellas in machining blanks having a comparatively low stiffness.

Known in the art is a tool for finishing internal surfaces of revolutionin blanks by the method of plastic deformation mounted for a lineardisplacement along the geometrical axis of the surface being machinedcomprising a body in the form of a body of revolution having at theperipheral surface thereof at least one annular groove for accommodationof deforming members each comprising a body of revolution mounted forrotation about their geometrical axes and for displacement along thegroove.

In this known tool, the body comprises a stepped cylinder provided witha bush with a tapered outer periphery fitted on one of the steps of thecylinder having an intermediate diameter. Mounted on the step of thebody of the largest diameter is a cylindrical bush which is axiallymovable relative to the body. The portion of the body adjacent to theend thereof has the smallest diameter and is provided with a sleeveaxially movable relative to the body, the outside diameter of the sleevecorresponding to the outside diameter of the cylindrical bush fitted onthe body.

The portion of the body adjacent to the other end thereof is adapted forclamping the tool in the tail spindle of a lathe.

A plurality of deforming members are uniformly circumferentially spacedbetween the opposite end faces of the cylindrical bush and sleeveforming a groove, the deforming members resting against the conicalsurfaces of the bush fitted on the body during the operation with thetool.

In order to maintain equal spacing between the deforming members, thelatter are mounted in a cage, and thrust bearings are placed either sideof the cage. The outer race of one bearing rests against the end face ofthe sleeve, and the outer race of the other bearing is supported at theend face of the cylindrical bush.

The body is provided with a centrally located hole through which adrawbar is passed. One end of the drawbar has a threaded portion forfastening the sleeve having a hole in its bottom wall for passing thedrawbar therethrough. The other end of the drawbar has a hole drillednormally to the axis thereof, and a pin is pressfitted into the hole.The tool body is provided with a recess normal to the longitudinal axisthereof for accommodating the pin, the recess having the width allowingan axial displacement of the pin together with the sleeve and drawbarrelative to the body. The pin ends are received in holes made in thecylindrical bush.

The sleeve and cylindrical bush are fastened by means of nuts, one nutbeing screwed on the end of the drawbar extending beyond the sleeve andthe other nut being screwed to the body. The body is also provided witha passage for supplying cooling lubricant to the deforming members andto the thrust bearings.

The deforming members comprise balls.

During the operation with the tool, the deforming members come incontact with the surface of a blank being machined which is clamped inthe lathe chuck. The tool in this case is mounted in the tail stockspindle of the lathe in coaxially with the surface being machined. Sincethe diameter of a circle enveloping the deforming balls is greater thanthat of the surface being machined by a predetermined amount of theinterference fit, the deforming balls are jammed between the conicalsurface of the bush and the surface being machined upon the axialdisplacement of the tool to work down microscopic irregularitiesthereof. The feed force is transmitted to the tool body and thence toeach deforming ball via the cylindrical and conical bushes and thethrust bearing.

At the points of contact of the deforming balls with the surface beingmachined, surface of the conical bush and the race of the thrust bearingthere are developed pressures resulting in considerable friction forcesand temperature rise. In order to decrease friction forces andtemperature rise, as well as to improve the finish of the surface beingmachined, coiling lubricant under pressure is supplied to the contactpoints through the hole in the body.

During the machining of the surface by the deform ing members, thesurface is cold-worked and strengthened.

Upon the completion of machining, the tool is retracted into the initialposition. During the return stroke of the tool, the balls are firsturged against the surface being machined to be slightly displaced underthe action of this force along the generatrix of the conical bush in thedirection towards the portion thereof of a smaller diameter so thatduring further movement of the tool the balls will never engage themachined surface.

The above-described prior art tool has a number of disadvantages one ofwhich consists in the permanent rigid contact of the deforming memberswith the surface being machined, surface of the conical bush and thecage which is due to the fact that the deforming members are received inthe bore being machined with an interference fit. This results inimportant radial forces whose value depends on a fit, initial finish ofthe surface being machined amount of the tool feed and required finishclass, characteristic of the material being machined. Where thedeforming member is made in the form of a ball, the amount of the radialforce exerted to each ball is within the range from 0.75 to 3.0 kN, andfor the rollers from 1.8 to 7.0 kN. The development of such forcesresults in a rapid wear of the conical surface of the bush and of thedeforming members themselves. This requires frequent replacement ofthese parts since their worn surfaces negatively affect the quality andprecision of the machined surface.

In addition, the above-mentioned values of the radial forces developedduring the machining create the conditions in which only blanks havingsufficient stiffness and strength can be machined.

The known construction of the tool allowing for the development ofconstant radial forces only to be applied to the surface during themachining, there is no opportunity of obtaining various performances asregards the precision and quality of different portions of the surfacebeing machined. This also constitutes a disadvantage of the known tool.

Another disadvantage of the known tool resides in the fact that itpermits to machine parts of one and the same diameter only for which theamount of projection of the deforming members has been once adjusted.

Still another disadvantage of the known tool consists in that during thereturn stroke of the tool into the initial position the deformingmembers are displaced along the generatrix of the conical bush in thedirection towards the smaller diameter thereof without contacting thesurface being machined, whereby only the direct stroke of the tool canbe used to machine the surface.

Since during the operation friction is developed at the points ofcontact of the deforming members with the surface being machined,surface of the conical bush and cage, as well as with the thrust bearingrace resulting in a temperature rise, cooling lubricant should beemployed to prevent the effects thereof changes in the structure of thematerial of the deforming members and the wear thereof, and the qualityof the surface being machined. This complicates the construction of thetool.

Furthermore, rather stringent requirements are imposed on the precisionand geometrical shaped of the deforming members so that standard ballsor rollers cannot be used independent on the precision grade thereof.

It is an object of the present invention to provide a tool for finishinginternal surfaces of revolution in blanks having such a constructionwhich permits to obtain parts of a high precision and to machine blankshaving a comparatively low stiffness and strength and high hardness, aswell as thin-walled blanks.

Another object of the invention is to provide a tool which permits toimprove the productivity of machining, is more reliable and simple inoperation.

The above objects are accomplished in a tool for finising internalsurfaces of revolution in blanks by the method of plastic deformationmounted for an axial movement along the geometrical axis of the surfacebeing machined and comprising a body in the form of a body of revolutionhaving at the peripheral surface thereof at least one annular groove foraccommodation of deforming members each comprising a body of revolution,the deforming members being mounted for rotation about their owngeometrical axes and for displacement along the groove, wherein,according to the invention, the body is provided with a centrallylocated axial hole communicating with at least one passage ex tending ina plane passing transversally with respect to the bottom wall of thegroove, the passage being directed substantially tangentially withrespect to the bottom wall of the groove and serving to supply fluidunder pressure to the deforming members which are displaced along theannular groove and rotate about their axes under the action of thefluid.

Due to the free accommodation of the deforming members in the groove anddue to the fact that they are moved therein under the action of fluidunder pressure and perform oscillations in the radial direction withrespect to the surface being machined and therealong, as well as rockingmotions each about its own center of gravity. This contributes to thereduction of a force required for plastic deformation of the blankmaterial.

In addition, during the operation of the tool, the pressure of fluidsupplied to the deforming members can be varied so that thin-walledblanks may be machined, and portions having different quality of finishmay be obtained on one and the same surface being machined.

Since the deforming members in the tool according to the invention areradially movable, it is now possible to machine elliptical and conicalsurfaces, as well as surfaces of revolution with a curvilinear orundulated generatrix.

During the operation of the tool, fluid under pressure fed to thedeforming members is concurrently used as coolant whereby the effects ofthe temperature changes on the surface being machined and deformingmembers are completely eliminated.

According to one embodiment of the invention, the body is made compositeof three parts: a sleeve and two disks fitted thereon having theiropposite flat ends defining the side walls of the groove, at least onedisk being mounted on the sleeve for an axial movement relative theretoso as to vary the width of the groove.

This embodiment permits to employ deforming members of differentdiameters in one and the same tool depending on specific application andon the requirements to the quality of the surface after the machining.

In another embodiment one of the disks is provided, at the peripheralportion of its flat end facing the end face of the other disk, with anannular projection for retaining the deforming members within the grooveafter the tool is retracted from the blank. While the amount ofprojection of the deforming members in the radial direction is somewhatlimited in this embodiment of the tool, the tool becomes more convenientin operation.

Where a blank has a comparatively low stiffness and strength, balls arepreferably used as deforming members. The ball has a point contact withthe surface being machined so that high contact pressures can bedeveloped sufficient to machine the blank.

Where each deforming member comprises a roller, it is possible toimprove the productivity of machining of the surface due to the factthat a roller has a line contact with the surface being machined so thatthe feed of the tool may be increased. However, the radial forces on thepart of the deforming rollers applied to the surface being machined areconsiderably greater than in the case of balls.

In all applications of the tool according to the invention for machiningsurfaces, the construction of the tool permits to utilize both thedirect and return stroke of the tool due to the fact that the contact ofthe deforming members with the surface being machined is provided byfeeding fluid under pressure to the deforming members.

The invention will now be described with reference to specificembodiments thereof illustrated in the accompanying drawings, in which:

FIG. 1 shows a partial axial section of a tool for finising internalsurfaces of blanks according to the invention;

FIG. 2 is a sectional view taken along the line IIII in FIG. 1;

FIG. 3 shows a partial axial section of another embodiment of the toolaccording to the invention;

FIG. 4 is a sectional view taken along the line I\/IV in FIG. 3;

FIG. 5 shows an axial section of the tool according to the inventionwith means for catching the deforming members;

FIG. 6 is a sectional view taken along the line VIVI in FIG. 5;

FIG. 7 shows a partial axial section of still another embodiment of thetool according to the invention;

FIG. 8 is a further embodiment of the same tool;

FIG. 9 shows a sectional view taken along the line IX-IX in FIG. 8;

FIG. shows a partial axial section of an embodiment of the toolaccording to the invention;

FIG. 11 is a sectional view taken along the line XI-Xl in FIG. 10;

FIG. 12 is a partial axial section of another embodiment of the toolaccording to the invention;

FIG. 13 is a sectional view taken along the line XIII- xn1 in FIG. 12.

The tool for finishing internal surfaces of revolution in blanks by themethod plastic deformation comprises a body 1 (FIG. 1) in the form of acylinder.

An annular groove 2 for accommodation of deforming members 3 is made onthe peripheral surface of the body I normally to the axis thereof. Inthis example the deforming members comprise balls. The diameter of ballsis taken depending on the blank material, class of finish of the surfacebeing machined, its shaped and other factors influencing the operatingconditions for the machining. The side walls of the groove 2 are flat,and the distance therebetween, that is the width of the groove 2 isselected to be sufficient for free accommodation of the deformingmembers 3 therein. Thus, for a tool of 80 mm diameter with the diameterof the deforming members of 12.7 mm, the space between the ball and oneof the side walls of the annular groove is of I mm when the ball is incontact with the other side wall.

The depth of the annular groove 2 is selected to be slightly greaterthan the dimension of the deforming member 3. The circumferentialspacing of the deforming members 3 is selected in such a manner as toeliminate the possibility of the accommodation of the members 3 withouta spacing therebetween during the operation of the tool. The deformingmembers 3 are mounted in the groove 2 for rotation about theirgeometrical axes and for displacement along the groove.

The body 1 is provided with a cylindrical shank 4 adjoining the body Iand aligned therewith. The shank 4 is adapted to fix the tool in amandrel 5 which is, in turn, mounted in the tail spindle ofa lathe (notshown). The mandrel 5 has a blind cylindrical bore 6 for accommodationof the shank 4, the bore having one portion with a flat surface and theother portion with a thread.

According to the invention, the body I and the shank 4 are provided witha centrally located axial hole 7. The hole 7 communicates with passages8 (FIG. 2) extending in a plane passing transversally with respect tothe bottom wall of the groove 2 and directed substantially tangentiallywith respect to the bottom wall of the groove. The passages 8 serve tosupply fluid under pressure to the deforming members 3.

The mandrel 5 is provided with a passage 9 (FIG. 1) comminicating withthe bore 6 thereof for connecting a flexible hose thereto (not shown) tocommunicate the hole 7 of the body 1 with a source of fluid underpressure (not shown).

In order to facilitate the manufacture, the axial hole 7 of the body 1is made as through hole and is plugged at 10. The plug 10 has a conicalthread for preventing it from loosening during the operation of thetool. A heat 11 of the plug 10 projecting beyond the body 1 is of ahexagonal shape for screweing the shank 4 of the body 1 into the mandrel5.

The outside diameter of the body 1 of the tool is selected to beslightly smaller than that of the bore of a blank 12 to be machined, theblank being clamped in the chuck of a lathe (not shown).

FIG. 3 shows another embodiment of the invention. In this embodiment,the tool comprises a body 13 which is also made in the form of a body ofrevolution. The body 13 is made composite of three parts: a sleeve 14and two disks 15 fitted thereon. The flat ends of the disks 15 facingeach other .define side walls of the groove 2. The disks 15 are mountedfor displacement along the axis of the sleeve 14 to vary the width ofthe groove 2. For assembly of the disks 15, the outer periphery of thesleeve 14 is provided with an annular flange 16, the disks 15 beingarranged at either side of the flange along the sleeve and resting withtheir flat ends against flat laterla sides of the flange 16. The widthof the groove 2 is selected depending on the diameter of the deformingballs 3 accommodated therein. The width of the groove 2 is varied byselecting the thickness of an annular washer 17 mounted between theadjacent flat surfaces of one of the disks l5 and lateral side of theannular flange 16. The disks 15 are fixed to the sleeve 14 by means ofnuts 18 and a locking nut 19, and for that purpose a thread is made oncorresponding portions of the outer peripheral surface of the sleeve 14.

The sleeve 14 is made integral with the shank 4 which is also used tofix the tool in the mandrel 5. A centrally located axial hole 20 is madein the body of the sleeve and in the shank 4 communicating with the bore6 in the mandrel 5 and, hence, with the passage 9 serving to supplyfluid under pressure to the deforming members 3. For that purpose thesleeve 14 has passages 21 (FIG. 4) extending in a plane passingtransversally with respect to the bottom wall of the groove 2communicating with the hole 20.

To facilitate the operation of the tool, one of the disks 15 (FIG. 3),which is the left one in this example (as show in the drawing), isprovided, at the periphery of its flat end facing the end of the otherdisk 15, with an annular projection 22 of a triangular cross-sectionserving to retain the deforming members 3 within the groove 2 during theretraction of the tool from the blank 12. It should be, however notedthat in this embodiment of the tool the amount of projection of thedeforming, member-s 3 is somewhat smaller than in the tool shown in FIG.1.

To facilitate the operation of the tool, there is provided means 23(FIG. 5) for catching the deforming members 3 during the retraction ofthe tool from the bore being machined. Where the surface of a blank 23abeing machined has an undulated generatrix, only the tools having flatside walls of the groove can be used, and the amount of projection ofthe deforming balls 3 beyond the outlines of the body 13 shouldapproximate one half of the diameter of the ball 3 during the machining.In machining surfaces with an undulated generatrix, the height of theundulation generally should not be greater than one half of the diameterof the ball 3. The diameter of the ball 3 is selected to be such thatthe minimal radius of curvature of a curvilinear of undulated generatrixof the surface does not exceed the radius of the ball.

The above-mentioned means 23 prevents the balls 3 from leaving thegroove 2 during the retraction of the tool from the blank 12. This means23 comprises a cylindrical bush 24 having the inside diameter which isslightly smaller than the maximum diameter of the body 13 of the tool.The bush 24 is provided at both ends thereof with annular projections 25for mounting thereon the ends of two diametrically opposed leaf springs26 arranged inside the bush 24. In order to accommodate the springs 26,the internal surface of the bush 24 is provided with rectangular slots27 (FIG. 6) extending along the generatrix of the bush. During theoperation, the bush 24 (FIG. is mounted coaxially with the tool and thebore being machined and is fixed in a bracket 28 by means of a lockscrew 29 mounted in a through hole of the bracket 28 normal to the axisof the bush 24. The end of the lock screw 29 is received in a recess inthe peripheral surface of the bush 24. The bracket 28 is rigidly fixedto the stand of a lathe (not shown).

In case when one pass of the tool is insufficient to obtain the surfacewith a required class of finish and precision, a multiple tool is usedwhich is illustrated in FIG. 7. The tool has a body 30 with two grooves2 on the periphery thereof, each groove being formed by the lateral sideof an annular rib made on the periphery of the body 30 and separatingone groove 2 from the other groove, and a disk fitted on the body 30.Deforming members 3 of different diameter are accommodated in thegrooves, the diameters being selected depending on the size of a blank,stiffness and strength thereof, geometrical accuracy of the surface tobe machined, with due consideration of the requirement of the permanentcontact with the surface. As to the remaining points, this constructionof the tool is identical with that shown in FIG. 3.

In all the abovedescribed embodiments balls are used as the deformingmembers 3. Such tools may be used to create high specific pressuresapplied to the surface being machined with comparatively low radialforces acting on the balls, thus contributing to the efficient machiningof blanks having relatively low strength and stiffness. For machiningstronger and stiffer blanks, it is advantageous to employ a tool inwhich the deforming members comprise rollers, because in this case, dueto their line contact with the surface being machined, greater linearfeeds of the tool are possible, whereby the productivity of themachining in improved. However, the rollers can be used only formachining surfaces with the rectilinear generatrix. In addition, therollers develop considerably greater radial forces transmitted to thesurfaces being machined as compared to the balls, whereby very strongand stiff blanks may be machined.

FIG. 8 shows the construction of a tool with the deforming members 3comprising rollers. This construction does not substantially differ fromthe construction of the tool shown in FIG. 1, with the only differencethat the passages 8 (FIG. 9) are arranged in two relatively parallelplanes extending through the bottom wall of the groove 2 (FIG. 8). Theshape of the groove 2 is selected in such a manner as to provide forfree displacement of the rollers 32 along the groove 2, and the spacebetween the surface being machined and the outer surface of the body 1is selected such that the 5 jamming of the rollers 32 therebetween isprevented.

In machining spherical surfaces, such as raceways of bearing races, thetool shown in FIG. 10 is preferably employed. The tool has a body 33 inthe form of a stepped cylinder with an annular groove 2 of a rectangularcross-section made in the portion of the cylinder having the largestdiameter. The plane, in which the groove 2 is arranged, is inclined withrespect to the longitudinal axis of the body 33. The diameter of thisportion of the body 33 is selected to be slightly smaller than thesmallest diameter of the spherical surface of a bearing race 34 beingmachined as measured normally to the body axis. The angle of inclinationof the groove 2 is equal to one half of the angle of arc of thespherical surface being machined with the center located substantiallyat the axis of the tool body 33. Passages 35 (FIG. 11) communicatingwith the hole 7 of the tool body 33 serving to supply fluid underpressure to the deforming members 3 are of an arcuate shape so that theoutlet portion thereof is tangential to the bottom wall of the groove 2.The remaining features of this construction of the tool are identicalwith those of the tool shown in FIG. 1.

For machining conical surfaces, including those having an undulatedgeneratrix, a tool of the construction shown in FIG. 12 is used. Thetool comprises a body 36 whose outer periphery is made conical with thetaper angle about equal to the taper angle of the surface being machinedof a blank 37 which is vertically mounted on the table of a drill stand(not shown).

Three annular grooves 38 for accommodation of the deforming members 3are provided on the peripheral surface of the body normally to the axisthereof. The width and depth of the grooves 38 are selected based on thesame conditions as those considered for the grooves 2 of the tool shownin FIG. 1. Depending on the selected diameter of the deforming members3, the distance between the adjacent grooves 38 is selected in such amanner that the difference in the diameters of the sections of theconical body 36 normally to the axis thereof passing through the middlesof the bottom walls of the adjacent grooves 38 does not exceed thediameter of the deforming member 3.

A cylindrical shank 39 made integral with the body 36 is locatedadjacent thereto at the side of the larger base of the cone, the freeend of the shank being tapered for insertion into a mandrel 40 which isclamped in the chuck of a drill stand (not shown). A hole 41 is made inthe body 36 and in the shank 39 which is plugged at 42 adjacent to thesmaller base of the cone. A passage 43 communicating with the hole 41 ismade in the wall of the shank 39 and serves to supply fluid underpressure from a source (not shown). For feeding the fluid to thedeforming members 3 from the hole 41, there are provided passages 44communicating therewith and extending in planes passing through thebottom walls of the grooves 38. The arrangement of the passages 44 inone of such planes is shown in FIG. 13.

In order to retain the deforming members 3 within the grooves 38 of thetool body 36 during the retraction thereof from the machined blank, anannular recess 45 is provided in the side wall of each groove locatedcloser to the cone apex, the defonning members 3 being received in thisrecess after the deforming members 3 being received in this recess afterthe interruption of the supply of fluid under pressure. In order toretain the deforming members 3 withing thegrooves 38 in the initialposition before the beginning of the operation, there is provided acylindrical bush 46 mounted above the blank 37 coaxially therewith. Thetool operates as follows. The tool is mounted in alignement with thebore of the blank 12 being machined in such a manner that the lowerdeforming members 3 (as shown in the drawing) contact the surface beingmachined and are partially received in this bore at a heightcorresponding to onehalf of the diameter. The blank 12 is caused torotate, and a linear motion is imparted to the tool. At the same time,fluid under pressure is fed from a source thereof to the bore 6 of thebody 1 and further, via the passage 8, into the groove 2 to thedeforming members 3. Fluid under pressure comprises compressed air.Under the action of compressed air, the deforming members 3 start movingalong the groove 2, while rotating about their own geometrical axes. Inaddition, the deforming members 3 are displaced in the radial directionaway from the axis of the tool until they contact the surface beingmachined. During the rotation, each of the deforming members is actedupon by a centrifugal force applied to the surface being machined at thepoints of contact to plastically deform the material. The deformingmembers 3 work down microscopic irregularities of the surface beingmachined. It has been found by way of experiments that the deformingmembers 3 also perform axial and radial oscillations along with therocking movement each about its own center of gravity under the actionof fluid under pressure.

This compound motion contributes to the reduction of the radial forcerequired for plastic deformation of material of the blank 12. During theoperation with the tool, compressed air is also utilized as coolant thuseliminating the effects of the temperature on the material of the blank12 and deforming members 3. This is particularly important inmanufacturing parts with high precision. In machining surfaces with suchtool, a relief pattern of the surface also may be obtained for partsoperating under thermal loads, eg in engine cylinder liners.

The use of fluid under pressure for moving the deforming members 3permits to control the value of the centrifugal force acting thereon byvarying the pressure of fluid depending on the requirements imposed onthe surface being machined. This provides an opportunity of obtaining aplurality of portions of one and the same bore having different qualityof finish.

Upon the completion of machining of the blank 12, the tool is returnedinto the initial position. For that purpose, the supply of compressedair to the bore 6 of the body 1 is interrupted. Where the return strokeof the tool should be used for repeated machining of the surface, theinterruption of compressed air supply is effected after the tool iscompletely retracted from the bore being machined.

When using means 23 (FIG. the linear displacement of the tool continuesuntil all the deforming members 3 are inside the cylindrical bush 24. Ifthe tool is to be removed from the machine, the tool body I isintroduced into the bush 24 until the projection of the leaf spring 26enters the groove 2, whereafter the lock screw 29 is screwed out of therecess of the surface of the bush 24. Then the tool is removed alongwith the means 23. v

' 'The operationof the tools shown in FIGS. 3, 7 and 8 is substantiallyindentical with that of the tool shown n no. 1.

In machining surfaces with an undulated generatrix, thedeforming members3 (FIG. 5) contact the surface being machinedover the entire profilethereof and are urged thereagainst under the action ofa centrifugalforce developed due to their rotation about the tool axis, that is theirdisplacement along the groove 2. The amount of projection of thedeforming members 3 is, in this case, variable in conformity with theshape of the surface. The height of undulation does not exceed one halfof the diameter of the deforming member 3.

The machining of a spherical surface is performed with no linearmovement of the tool, since during the rotation of the race 34 (FIG. 10)all points of the inner spherical surface thereof will contact thedeforming members 3. For that purpose, the tool is introduced, prior tothe operation, into the race 34 until the center of the sphericalsurface thereof coincides with the center of a circle described by thedeforming members 3 during their displacement along the groove 2.

Upon the completion of machining, the tool is retracted from themachined race 34, and the deforming members 3 are catched by the means23 as described above.

In machining conical surfaces the tool and the blank 37 are mounted inthe vertical position, and the tool is introduced into the bore beingmachined moving it downwards at an amount corresponding to the distancebetween two adjacent grooves 38. Then compressed air is fed through thepassage 43 into the hole 41, wherefrom it is admitted, via the passages44, into the grooves 38, and hence, to the deforming members 3. The bush46 retains the deforming members 3 from leaving the grooves 38. As thetool moves axially in the bore being machined, the amount of projectionof the deforming members 3 is gradually changed from the value aboutequal to one half of their diameter to the value equal to one half ofthe difference in the diameters of the body 36 and the bore beingmachined in one and the same section. Therefore, the machining of thewhole bore is effected within the limits of the displacement of the tooldefined by the distance between two adjacent grooves 38.

Upon the completion of machining, the supply of compressed air to thedeforming members 3 is interrupted, whereby they roll down under theirown gravity into the recesses 45 to the bottom wall of their respectivegroove 38. Then the tool is moved upwards until the complete retractionfrom the part being machined.

What is claimed is:

l. A tool for finishing internal surfaces of revolution in blanks by themethod of plastic deformation mounted for a linear displacement alongthe geometrical axis of the surface being machined comprising: a body inthe form of a body of revolution; at least one annular groove in theperipheral surface of said body; deforming members, each comprising abody of revolution accommodated in said groove for displacementtherealong and for rotation about their own geometrical axes; said bodyhaving a centrally located axial hole; at least one passagecommunicating with said hole in said body, said passage extending in aplane passing transversally with respect to the bottom wall of saidbeing mounted on the sleeve for displacement along the axis of thesleeve so as to vary the width of the groove.

3. A tool as claimed in claim 2, wherein one of the disks is provided,at the peripheral portion of its flat end facing the end of the otherdisk, with an annular projection for retaining the deforming memberswith the groove during the retraction of the tool from the blank.

1. A tool for finishing internal surfaces of revolution in blanks by themethod of plastic deformation mounted for a linear displacement alongthe geometrical axis of the surface being machined comprising: a body inthe form of a body of revolution; at least one annular groove in theperipheral surface of said body; deforming members, each comprising abody of revolution accommodated in said groove for displacementtherealong and for rotation about their own geometrical axes; said bodyhaving a centrally located axial hole; at least one passagecommunicating with said hole in said body, said passage extending in aplane passing transversally with respect to the bottom wall of saidgroove, the passage being directed substantially tangentially withrespect to the bottom wall of said groove and serving for supplyingfluid under pressure to said deforming members which are displaced alongsaid groove and rotate about their own geometrical axes under the actionof the fluid.
 2. A tool as claimed in claim 1, wherein the body is madecOmposite of a sleeve and two disks fitted thereon, the flat ends of thedisks facing each other defining the side walls of the groove, at leastone disk being mounted on the sleeve for displacement along the axis ofthe sleeve so as to vary the width of the groove.
 3. A tool as claimedin claim 2, wherein one of the disks is provided, at the peripheralportion of its flat end facing the end of the other disk, with anannular projection for retaining the deforming members with the grooveduring the retraction of the tool from the blank.